In general liquid crystal display devices, polarity inversion drive is performed in order to suppress liquid crystal deterioration. A known polarity inversion drive scheme is a scheme (frame inversion drive scheme) in which the polarity of a voltage applied to the liquid crystal is inverted every frame. However, this drive scheme is subject to display defects, such as flicker, upon display, and therefore, in the drive schemes employed in recent years, the polarity of an applied voltage is inverted every horizontal scanning signal line and also every frame (a so-called “line inversion drive scheme”) or the polarity of an applied voltage is inverted every two vertically/horizontally adjacent pixels and also every frame (a so-called “dot inversion drive scheme”).
The dot inversion drive scheme uses a relatively complicated anti-flicker pattern, and therefore, is resistant to flicker, so that high-quality display can be achieved. Moreover, in this scheme, a direct-current voltage is applied to a common electrode of a liquid crystal panel, and therefore, less noise occurs than in the scheme where the common electrode is driven by an alternating-current voltage.
However, in such a dot inversion drive scheme where a direct-current voltage is applied to the common electrode, the polarity of a video signal to be applied to the liquid crystal panel is switched between predetermined voltages respectively above and below the potential of the common electrode, and therefore, the voltage swing of a video signal outputted by a liquid crystal panel driver is large, so that a specialized power supply configuration is required and power consumption tends to be high. Moreover, in the line inversion drive also, more power consumption can be saved as the polarity inversion cycle of a video signal becomes longer (i.e., as the number of inversions per frame decreases).
Accordingly, for example, Japanese Laid-Open Patent Publication No. 2009-14965 discloses a configuration in which only the odd scanning lines are sequentially selected during a first field in order to output signals from a source driver, and thereafter, polarity inversions occur during the following field, i.e., second field, so that only the even scanning lines are sequentially selected in order to output signals from the source driver. In this manner, line inversion drive or dot inversion drive can be realized by simply performing one polarity inversion operation per frame. Such a drive scheme is called an interlaced scanning scheme or an interlacing drive scheme.